Actuating pistons which serve in hydraulic systems for the transmission of a stroke movement are subjected to a pretension, which is usually generated by a spring.
This ensures that the information arriving at the actuating or control piston, which is aimed at effecting a change in the stroke position, is processed without delay and without falsification.
The disadvantages of such a design are to be seen in that, when there is a deformation of the control spring, the upper spring pad on the spring plate side no longer remains parallel to the lower pad. The resultant friction between the spring plate and the nut serving as connecting element between spring plate and actuating piston may mean that the control spring cannot adjust unassisted at its spring plate end due to the new position resulting from the spring deformation (spring travel):
The spring "sticks". The friction torque generates a radial force in the guide of the actuating piston, which has an adverse effect on the intended delay-free and unfalsified change in the stroke position of the actuating piston.